The present invention relates to fuel dispensers, fueling systems and, more particularly, to a scheme for monitoring vapor recovery lines in a fueling system.
In response to ever increasing governmental pressures and regulations, the petroleum industry has increasingly made provision for recovering fuel vapors that are displaced from a fuel tank as fuel is discharged therein. Generally, there are two types of systems designed for vapor recoveryxe2x80x94pressure balance recovery systems and vacuum assist vapor recovery systems.
Pressure balance systems involve the addition of a vapor return conduit system that extends from a dispenser nozzle, through a hose, to the dispenser pedestal and then through an underground conduit system to a point of disposal. Most frequently, the means of disposal was simply to return the vapors to the storage tank from which fuel was drawn to fill the fuel tank of the vehicle. As fuel is withdrawn in fueling a vehicle, the vapor space in the storage tank is increased. Conversely, as fuel is introduced into the fuel tank of a vehicle, vapor space is decreased to essentially an identical extent. The pressure differentials thus created cause the vapors to flow through the vapor conduit system from the nozzle back into the storage tank, thereby creating a pressure balance.
Most nozzles for pressure balance vapor recovery systems comprise a bellows or boot that surrounds the nozzle""s spout. In delivering fuel, the spout is inserted into the inlet pipe of a vehicle fuel tank and the bellows is compressed to form a vapor seal with the inlet pipe. The bellows forms, in combination with the spout, an annular passage, which is the initial portion of the vapor return, conduit system. Vapors then flow through internal passages in the nozzle body to the hose end thereof. In most instances, the hose is of the coaxial type, with a central fuel passage and a surrounding coaxial vapor return passage, being formed by flexible tubes. The coaxial hose is connected by a fitting to the side of the dispenser pedestal. Vapor recovery lines within the pedestal connect with further vapor return lines, usually extending underground, that return the vapors to the storage tank.
Vacuum assist systems also employ vapor recovery lines but a vacuum assist is added to enhance the return of displaced vapors to the storage tanks. The vacuum assist also eliminates the need to rely upon a compression seal between a bellows and fuel tank inlet pipe. In most cases, the bellows is eliminated, since the vacuum of the vapor system is sufficient to draw substantially all of the displaced fuel vapors into inlet openings in the distal end of an essentially rigid spout, or in the spout end of the nozzle body. Vacuum assist nozzles also include a vapor return passage, usually formed interiorly of the nozzle body, for connection with a coaxial hose, at the opposite end of the nozzle.
Current vapor recovery systems do not provide an adequate means for monitoring vapor recovery or detecting possible obstructions or blockage of vapor recovery passages. Vapor recovery passages could potentially be blocked by condensed vapor or particulate matter, leading to inefficient or ineffective vapor recovery. Accordingly, there is a need for a scheme that enables monitoring of vapor recovery processes in a fuel dispensing system.
This need is met by the present invention wherein a vapor recovery line monitor is provided. In accordance with one embodiment of the present invention, a vapor recovery line monitor is provided comprising a fuel dispensing and vapor recovery hose, a pressure sensing passage, and a pressure transducer. The fuel dispensing and vapor recovery hose defines a fuel dispensing passage and a vapor recovery passage. The pressure sensing passage defines a pressure sensing orifice. The pressure sensing orifice is positioned within the vapor recovery passage. The pressure transducer is coupled to the pressure sensing passage and is configured to provide an indication of pressure at the pressure sensing orifice.
The fuel dispensing passage and the vapor recovery passage may be defined as coaxial passages within the hose. The vapor recovery passage may surround the fuel dispensing passage and the pressure sensing passage may be positioned within the vapor recovery passage.
The hose may extend from a fuel input end to a fuel dispensing end and the pressure sensing orifice may be positioned proximately to the fuel dispensing end of the hose. The hose extends from a fuel input end to a fuel dispensing end and includes a fuel dispensing nozzle at the fuel dispensing end. The pressure sensing orifice may be positioned within the fuel dispensing nozzle. The hose may also include a coupling arranged to define respective portions of the fuel dispensing passage, the vapor recovery passage, and the pressure sensing passage. The coupling may be a breakaway coupling.
The pressure transducer may comprise a dual input transducer having a first input coupled to the pressure sensing passage and a second input coupled to atmospheric pressure.
In accordance with another embodiment of the present invention, a fuel dispenser is provided comprising a fuel dispensing and vapor recovery hose, a meter, a fueling pedestal, and a vapor recovery line. The fuel dispensing and vapor recovery hose defines a fuel dispensing passage and a vapor recovery passage. The meter is configured to provide an indication of an amount of fuel dispensed through the hose. The fueling pedestal is configured to support the hose and the meter. The vapor recovery line monitor comprises a pressure sensing passage and a pressure sensing transducer. The pressure sensing passage defines a pressure sensing orifice positioned within the vapor recovery passage of the hose. The pressure transducer is coupled to the pressure sensing passage and is configured to provide an indication of pressure at the pressure sensing orifice.
In accordance with yet another embodiment of the present invention, a fuel dispensing system is provided comprising at least one fuel storage tank, at least one fuel dispenser, at least one fuel dispensing line configured to couple the fuel storage tank to the fuel dispenser, and at least one vapor recovery line configured to couple the fuel storage tank to the fuel dispenser. The fuel dispenser comprises a fuel dispensing and vapor recovery hose, a meter, a pedestal coupling, and a vapor recovery line monitor. The vapor recovery line monitor comprises a pressure sensing passage and a pressure transducer. The pressure sensing passage defines a pressure sensing orifice positioned within the vapor recovery passage of the hose. The pressure transducer is coupled to the pressure sensing passage and is configured to provide an indication of pressure at the pressure sensing orifice.
A plurality of pressure transducers may be configured to provide an indication of pressure at the pressure sensing orifice, within the vapor recovery line, the fuel storage tank, and the fuel dispenser. The pressure transducer may be coupled to a dispenser display and may be configured to provide an indication of pressure.
The fuel dispensing system may include a vacuum assist pump in communication with the vapor recovery passage and may further comprise an additional pressure transducer configured to provide an indication of operational characteristics of the vacuum assist pump.
The pressure transducer may be coupled to a controller and the controller may be configured to process pressure measurements received from the transducer. The controller may be configured to store pressure data taken over a predetermined time period and display the stored data. A plurality of a pressure sensing passages may be configured to define a plurality of diagnostic points within the vapor recovery passage. The controller may be configured to store pressure data taken at the plurality of diagnostic points and utilize the stored data in system diagnostics.
Accordingly, it is an object of the present invention to provide a scheme for monitoring vapor recovery processes in a fuel dispensing system. Other objects of the present invention will be apparent in light of the description of the invention embodied herein.